This invention relates to a class of metal complexes, the ligands used to prepare these metal complexes and to olefin polymerization catalysts derived therefrom that are particularly suitable for use in a polymerization process for preparing polymers by polymerization of xcex1-olefins and mixtures of xcex1-olefins. Additionally, the present invention relates to an improved olefin polymerization process useful for preparing polymers of prochiral olefins having a high degree of isotacticity and low polymer chain defect content. Such polymers possess a correspondingly high crystalline melting point
Metal complexes containing polydentate chelating ligands are well known in the art. Examples include complexes based on acetylacetonate (AcAc), tetramethylethylenediamine, and other polydentate chelating ligands. While such complexes with transition metals are well known in the art, seldom are such metal complexes useful as catalyst components for addition polymerizations, especially olefin polymerizations. Examples of previously known work in this field are found in WO 98/030612, Chem. Commun., 1998, 849, JACS, 1998, 120, 4049, and elsewhere.
Despite advances in the present art, there remains a need for metal complexes having improved catalytic properties. It would be advantageous to be able to produce polyolefins with improved physical properties. It would also be especially advantageous to be able to produce crystalline polyolefins, particularly crystalline, isotactic polypropylene or poly(2-butene) using polymerization catalyst compositions that give polymers of high crystallinity and few chain defects. Such polymers possess extremely high strength properties, particularly at high use temperatures.
According to the present invention there are provided metal complexes comprising a multidentate chelating ligand, said metal complexes corresponding to the formula: 
where M is a metal from one of Groups 3 to 13 of the Periodic Table of the Elements, the lanthanides or actinides;
T is nitrogen or phosphorus;
RA independently each occurrence is hydrogen, RB or Txe2x80x2 RBj,
RB independently each occurrence is a group having from 1 to 80 atoms not counting hydrogen, which is hydrocarbyl, hydrocarbylsilyl, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, hydrocarbylamino-substituted hydrocarbyl, or hydrocarbylsilyl-substituted hydrocarbyl, and optionally the RB and RA groups bonded to the same Txe2x95x90C grouping may be joined together to form a divalent ligand group;
j is is 1 or 2, and when j is 1, Txe2x80x2 is oxygen or sulfur and when j is 2, Txe2x80x2 is nitrogen or phosphorus,
RC independently each occurrence is hydrogen or a group having from 1 to 80 atoms not counting hydrogen, which is hydrocarbyl, hydrocarbylsilyl, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, hydrocarbylamino substituted hydrocarbyl, or hydrocarbylsilyl- substituted hydrocarbyl, or two RC groups are joined together forming a divalent ligand group;
X is an anionic ligand group having up to 60 atoms (excluding ligands that are cyclic, delocalized, xcfx80-bound ligand groups), and optionally two X groups together form a divalent ligand group;
Xxe2x80x2 independently each occurrence is a Lewis base ligand having up to 20 atoms;
x is a number from 0 to 5; and
xxe2x80x2 is zero, 1 or 2.
Also, according to the present invention, there is provided a catalyst composition for olefin polymerization comprising:
(A) a catalyst component comprising the foregoing metal complex; and
(B) a cocatalyst component comprising an activating cocatalyst wherein the molar ratio of (A) to (B) is from 1:10,000 to 100:1.
Further according to the present invention there is provided a process for the polymerization of olefins comprising contacting one or more C2-20 xcex1-olefins under polymerization conditions with one of the aforementioned catalyst compositions. A preferred process of this invention is a high temperature solution polymerization process for the polymerization of prochiral olefins comprising contacting one or more C3-20 xcex1-olefins under polymerization conditions with one of the aforementioned catalyst compositions at a temperature from 30 to 250xc2x0 C., more preferably from 50 to 220xc2x0 C., most preferably from 70 to 200xc2x0 C.
In a further embodiment of the invention, there is provided a polymerization process for preparing isotactic polypropylene having an isotacticity as measured by 13C NMR triads of greater than 75 percent, preferably greater than 85 percent, more preferably greater than 95 percent comprising contacting propylene at a temperature from 50 to 220xc2x0 C., preferably from 70 to 200xc2x0 C. under polymerization conditions with the foregoing catalyst composition.
Preferably, the metal, M, is a metal of Group 3 or 5-8 of the Periodic Table of the Elements.
Within the scope of this invention are the polyolefin and polypropylene products produced by the aforementioned processes. Preferred products have a high degree of crystallinity and relatively few polymer chain defects.
This invention also provides a multi-dentate chelating ligand corresponding to the formula: 
where the ligand is in the form of a free base capable of being deprotonated, a Group 1 or 2 metal salt, or a Group 2 metal halide salt.
Within the scope of this aspect of the invention is the use of one of these ligands of formula II for synthesis to produce a metal complex of formula I of this invention, or, more specifically, the use of one of these ligands of formula II for synthesis to produce a metal complex comprising a metal from one of Groups 3 to 13 of the Periodic Table of the Elements, the lanthamides or actinides, and at least 1 of the foregoing ligands of formula II.
The present catalysts and processes may be used in the solution or bulk polymerization, slurry polymerization or gas phase polymerization of ethylene/propylene (EP polymers), ethylene/octene (EO polymers), ethylene/styrene (ES polymers), propylene homopolymers, copolymers of propylene with ethylene and/or C4-10 xcex1-olefins, and ethylenelpropyleneldiene (EPDM copolymers) wherein the diene is ethylidenenorbornene, 1,4-hexadiene or similar nonconjugated diene. As previously slated, the catalysts are especially desirable for use in the polymerization of propylene to give isotactic polypropylene of high isotacticity.
The catalysts of this invention may also be supported on a support material and used in olefin polymerizatuon processes. The catalyst may also be prepolymerized with one or more olefin monomers in situ in a polymerization reactor or in a separate process with intermediate recovery of the prepolymerized catalyst prior to the primary polymerization process. Highly desirably, the catalyst compositions of the present invention produce highly isotactic polymers of prochiral xcex1-olefins, especially, propylene, having tacticity (as measured by repeat mm diadds in the 13C NMR spectrum) of greater than 95 percent, preferably greater than 96 percent. Further uniquely, the present invented polymerization process attains such highly isotactic polymers at polymerization temperatures greater than 70xc2x0 C., preferably greater than 90xc2x0 C. and the polymer has very low chain defects, preferably less than 0.1 mole percent, more preferably less than 0.01 mole percent. Such polymers are highly crystalline and have high crystalline mering points due to the uniform nature of the polymer chains.